1. Technical Field
The present invention relates to a micro lens array substrate, a method of manufacturing the micro lens array substrate, an electro-optical device and an electronic apparatus.
2. Related Art
An electro-optical device has been known that is equipped with an electro-optic material (for example, liquid crystal and the like) between an element substrate and an opposite substrate. A liquid crystal device used as a liquid crystal light valve of a projector can be among examples of the electro-optical device. An attempt has been made to realize high efficiency of utilization of light for such a liquid crystal device.
Incidentally, for example, a configuration has been known in which at least one of the element substrate and the opposite substrate of the liquid crystal device includes the micro lens array substrate and thus light incident on the liquid crystal device is gathered. The configuration accomplishes a substantial improvement on an aperture rate of the liquid crystal device. The micro lens array substrate includes a base material (substrate) made from quartz or the like, on whose surface multiple concave portions are formed, and a lens layer having a different refractive index from that of the base material, which is formed in such a manner as to fill in a concave portion covering the material (for example, refer to JPA-2011-118324).
Incidentally, if in the element substrate including the micro lens array substrate, a TFT element is formed after forming the micro lens array substrate, the micro lens array substrate is exposed to temperature changes, such as high temperature heating or cooling at the time of high temperature heating processing in a process of forming the TFT element. Then, a stress, which results from a difference in thermal expansion coefficient between the material and the lens layer, a change in composition of the lens layer, or the like, is applied to the lens layer. This causes a problem in that a crack propagates into the lens layer.
In contrast, like the configuration of the liquid crystal display element (electro-optical device) disclosed in JP-A-2011-118324, a configuration has been proposed in which the stress being applied to the lens layer is distributed and alleviated by separating the lens layer on the micro lens array substrate between lenses. However, according to the configuration of the liquid crystal display element disclosed in JP-A-2011-118324, because the adjacent lenses are arranged with spacing in between, light incident on a space between the lenses is not gathered by the lens. This causes a concern that the efficiency of utilization of light will be decreased. Therefore, the crack in the lens layer can be prevented, and additionally, the micro lens array substrate has been required that is capable of improving the efficiency of utilization of light.